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(#) WebView API Availability

!!! WARNING: WebView API Availability
   This is a warning.

Id
:   `WebViewApiAvailability`
Summary
:   WebView API Availability
Severity
:   Warning
Category
:   Correctness
Platform
:   Android
Vendor
:   Android Open Source Project
Feedback
:   https://issuetracker.google.com/issues/new?component=192708
Since
:   3.6.0 (February 2020)
Affects
:   Kotlin and Java files
Editing
:   This check runs on the fly in the IDE editor
See
:   https://developer.android.com/reference/androidx/webkit/package-summary
Implementation
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/WebViewApiAvailabilityDetector.kt)
Tests
:   [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/WebViewApiAvailabilityDetectorTest.kt)

The `androidx.webkit` library is a static library you can add to your
Android application allowing you to use new APIs on older platform
versions, targeting more devices.

(##) Example

Here is an example of lint warnings produced by this check:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text
src/test/pkg/WebViewActivity.java:14:Warning: Consider using
WebViewCompat.createWebMessageChannel instead which will support more
devices. [WebViewApiAvailability]
    webView.createWebMessageChannel();
    ---------------------------------
src/test/pkg/WebViewActivity.java:15:Warning: Consider using
WebViewCompat.postVisualStateCallback instead which will support more
devices. [WebViewApiAvailability]
    webView.postVisualStateCallback(0, null);
    ----------------------------------------
src/test/pkg/WebViewActivity.java:16:Warning: Consider using
WebViewCompat.postWebMessage instead which will support more devices.
[WebViewApiAvailability]
    webView.postWebMessage(null, null);
    ----------------------------------
src/test/pkg/WebViewActivity.java:17:Warning: Consider using
WebViewCompat.getCurrentWebViewPackage instead which will support more
devices. [WebViewApiAvailability]
    WebView.getCurrentWebViewPackage();
    ----------------------------------
src/test/pkg/WebViewActivity.java:18:Warning: Consider using
WebViewCompat.getWebChromeClient instead which will support more
devices. [WebViewApiAvailability]
    webView.getWebChromeClient();
    ----------------------------
src/test/pkg/WebViewActivity.java:19:Warning: Consider using
WebViewCompat.getWebViewClient instead which will support more devices.
[WebViewApiAvailability]
    webView.getWebViewClient();
    --------------------------
src/test/pkg/WebViewActivity.java:20:Warning: Consider using
WebViewCompat.getSafeBrowsingPrivacyPolicyUrl instead which will support
more devices. [WebViewApiAvailability]
    WebView.getSafeBrowsingPrivacyPolicyUrl();
    -----------------------------------------
src/test/pkg/WebViewActivity.java:21:Warning: Consider using
WebViewCompat.setSafeBrowsingWhitelist instead which will support more
devices. [WebViewApiAvailability]
    WebView.setSafeBrowsingWhitelist(null, null);
    --------------------------------------------
src/test/pkg/WebViewActivity.java:22:Warning: Consider using
WebViewCompat.startSafeBrowsing instead which will support more devices.
[WebViewApiAvailability]
    WebView.startSafeBrowsing(this, null);
    -------------------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here is the source file referenced above:

`src/test/pkg/WebViewActivity.java`:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers
package test.pkg;

import android.app.Activity;
import android.os.Build;
import android.os.Bundle;
import android.webkit.WebView;

public class WebViewActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (Build.VERSION.SDK_INT > 28) {
            WebView webView = findViewById(R.id.webview);
            webView.createWebMessageChannel();
            webView.postVisualStateCallback(0, null);
            webView.postWebMessage(null, null);
            WebView.getCurrentWebViewPackage();
            webView.getWebChromeClient();
            webView.getWebViewClient();
            WebView.getSafeBrowsingPrivacyPolicyUrl();
            WebView.setSafeBrowsingWhitelist(null, null);
            WebView.startSafeBrowsing(this, null);
        }
    }
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can also visit the
[source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/WebViewApiAvailabilityDetectorTest.kt)
for the unit tests for this check to see additional scenarios.

The above example was automatically extracted from the first unit test
found for this lint check, `WebViewApiAvailabilityDetector.testGuardedAndroidXAvailableMethods`.
To report a problem with this extracted sample, visit
https://issuetracker.google.com/issues/new?component=192708.

(##) Suppressing

You can suppress false positives using one of the following mechanisms:

* Using a suppression annotation like this on the enclosing
  element:

  ```kt
  // Kotlin
  @Suppress("WebViewApiAvailability")
  fun method() {
     problematicStatement()
  }
  ```

  or

  ```java
  // Java
  @SuppressWarnings("WebViewApiAvailability")
  void method() {
     problematicStatement();
  }
  ```

* Using a suppression comment like this on the line above:

  ```kt
  //noinspection WebViewApiAvailability
  problematicStatement()
  ```

* Using a special `lint.xml` file in the source tree which turns off
  the check in that folder and any sub folder. A simple file might look
  like this:
  ```xml
  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;lint&gt;
      &lt;issue id="WebViewApiAvailability" severity="ignore" /&gt;
  &lt;/lint&gt;
  ```
  Instead of `ignore` you can also change the severity here, for
  example from `error` to `warning`. You can find additional
  documentation on how to filter issues by path, regular expression and
  so on
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html).

* In Gradle projects, using the DSL syntax to configure lint. For
  example, you can use something like
  ```gradle
  lintOptions {
      disable 'WebViewApiAvailability'
  }
  ```
  In Android projects this should be nested inside an `android { }`
  block.

* For manual invocations of `lint`, using the `--ignore` flag:
  ```
  $ lint --ignore WebViewApiAvailability ...`
  ```

* Last, but not least, using baselines, as discussed
  [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).

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